Winter brings challenging conditions for managing herd health, nutrition

January and February bring some of the coldest days of the year, and March can bring some of the snowiest.

Cattle experience cold stress at different temperatures depending on conditions and coat length. The lower critical temperature (LCT) is an animal’s ability to withstand cold conditions. According to Penn State University Extension, the LCT is the temperature at which maintenance requirements increase to the point where animal performance is negatively affected.

You may think LCT only impacts animals in winter, however an animal with a wet summer coat at 60 degrees Fahrenheit can experience cold stress. Typically summer cold stress is short-lived and animals recover quickly with sunshine and a warm breeze. Winter temperatures prove to be more challenging to manage, as cold snaps can last for days, sometimes weeks. Early sub-freezing temperatures and long cold snaps can be the hardest on animals. Cows need to adapt to winter temperatures by transitioning from fall hair coats to winter coat. The heavy winter coat has a layer of insulation in it that traps air in between the hairs. A wet, saturated coat loses its insulation ability, causing the animal to suffer cold stress at a much higher temperature than she would if her coat were dry.

Research from Kansas State University shows the LCT of a cow with her full winter is approximately 20 degrees Fahrenheit. Research from North Dakota State University states that a cold-adapted cow in good body condition can have an LCT as low at -6 degrees Fahrenheit if conditions are dry and still. It goes without saying cold, windy and rainy conditions are stressful on cows. Minimizing exposure to unfavorable conditions will help your cows be more productive and efficient.

Wind breaks and dry bedding are essential in winter months. Beef cattle are quite adept to managing winter months without cover if need be. If you do provide a shed or barn for loafing, make sure it is well ventilated. Heavy condensation in barns or sheds can almost be as bad as rain, since moisture will accumulate on cattle and penetrate the dry insulation layer of the coat. Reducing contact with muddy yards and wet manure are also important management practices. An animal with manure or mud caked to its coat cannot combat cold, wind, and moisture, therefore requiring higher dry matter intakes.

Keeping cows in good body condition over winter helps her several ways. The ideal body condition score (BCS) of a late-term pregnant beef cow is 5-7. Research has shown that cows with ideal BCS maintain weight better, produce higher quality colostrum, and breed back faster than cows with lower BCS. A typical pregnant beef cow eats approximately 2.5% of her body weight in ideal conditions. A cold-stressed cow can require 1% or more dry matter intake for maintenance.

Once a beef cow calves, she will need increased energy to maintain BCS. There is a difference in beef cow milk production depending on breed and genetics, but a typical beef cow will produce about 1.5 gallons of milk per day. Be sure to keep a close eye on BCS of fresh cows in cold temperatures. She now must maintain her BCS while feeding a growing calf.

Don’t forget about the calves in the cold weather. A newborn calf can deplete its body fat stores within hours of birth if it is not up and nursing. Quality colostrum at first nursing is essential, and the sooner the calf nurses, the better. Newborn calves are born with a body temperature of about 103 degrees Fahrenheit. Body temperature quickly decreases after birth, which is why it is essential for the cow to lick the calf clean and allow the coat to dry. The longer the calf is cold stressed, the less likely it will survive. If a calf’s mouth gets cold before it nurses, it may not be able to suckle. The first feeding of colostrum heavily impacts the calf’s ability to survive. High risk calves, those born twins, from a difficult birth, or from malnourished cows require special attention. These calves are often weaker and may require help to dry off or nurse. Calves under extreme cold stress may require a calf blanket for a short time to help them adjust to their environment. Always provide plenty of dry bedding for cows and calves. Once calves are on the ground, you will need to provide additional bedding to make sure the little ones don’t need to compete with cow for a warm dry place to rest.

A successful calving season starts with a good foundation. Keep cows happy and healthy, and healthy calves will be your reward for good management.

Written by: Aerica Bjurstrom, UW-Madison Division of Extension Agriculture Agent Kewaunee County, article recently appeared in the Wisconsin Agriculturist

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